Introduction:
The cubical contents method, unit base method, and plinth area method are all widely used techniques for estimating construction costs. However, when it comes to the preparation of approximate estimates, the cubical contents method is considered to be more accurate than the unit base method and plinth area method.

Explanation:
The cubical contents method calculates the estimate based on the total volume or cubic contents of a building. This method takes into account the length, width, and height of the building, as well as the number of floors. By considering the total volume of the building, the cubical contents method provides a more accurate estimate of the construction cost.

On the other hand, the unit base method calculates the estimate based on the cost per unit area of the building. This method takes into account the total area of each floor, including the plinth area, and multiplies it by the cost per unit area. While this method is widely used and provides a quick estimate, it does not take into consideration the height or volume of the building. As a result, the estimate may not accurately reflect the actual cost of construction.

Similarly, the plinth area method calculates the estimate based on the plinth area of the building, which is the total built-up area at the floor level. This method is commonly used for residential buildings and calculates the estimate by multiplying the plinth area by the cost per unit area. However, like the unit base method, the plinth area method does not consider the volume of the building, leading to potential inaccuracies in the estimate.

Conclusion:
In conclusion, for the preparation of approximate estimates, the cubical contents method is more accurate than the unit base method and plinth area method. While the unit base method and plinth area method provide quick estimates, they do not take into consideration the volume of the building, which can lead to inaccuracies. Therefore, for a more precise estimate, the cubical contents method is recommended as it considers the total volume of the building.